GB1176816A - A Semiconductor Voltage Generator Analog to Digital and Digital to Analog Conversion Device. - Google Patents

Abstract

1,176,816. Analogue-to-digital converters. BENDIX CORP. 16 Nov., 1967 [21 Nov., 1966], No. 52267/67. Heading G4H. In apparatus for converting an analogue signal to digital signals, or vice versa, the signals are balanced by being compared in a magnetic core, the flux due to the analogue signal being opposed by the flux due to the digital signals, there being means to indicate when a balance has been reached. In an analogue to digital converter the unknown input signal Ei is applied to a winding 1 and signals corresponding to the digital output are applied to windings 19, 19A, 19B, 19C. In a gap in the core is a Hall-effect plate 43 which is fed with current from source 47 and gives an output Eo proportional to this current and the flux in the core. The output is amplified in logic circuit 31 and used to set one of two Schmitt triggers according to its polarity. The outputs of the triggers are combined in an Or gate and used to gate clock pulses to a counter. The direction of counting is determined by which of the two triggers is set. The counter stages give digital signals representing the input signal and each controls a switch, adapted when closed to apply a unit current to the corresponding winding 19, 19A, 19B, 19C. These windings have a number of turns weighted 1, 2, 4, 8 so that the value in the counter represents in binary scale the total flux generated in the core by the four windings. The counter counts up or down until a balance is reached and then stops, the flux in the core then being zero and the Hall plate giving no output. Instead of weighted windings, weighted currents may be used, or a combination of both. Digital-to-analogue converters.-A similar core is used to provide a digital-to-analogue converter, the digital signals being applied to weighted windings, or as weighted currents, to generate a corresponding flux as above. The output of the Hall effect plate is applied to an operational amplifier the output of which is applied to the analogue signal winding to cancel the flux. The analogue output increases until a balance is reached and then remains steady.